At present, contactless transceiver systems are widely used in numerous applications. One of these applications is the contactless smart card, which is being increasingly used in various sectors, such as the public transport sector, for example. They have also been developed as a means of payment.
The exchange of information between a contactless card and the associated reader is accomplished by remote electromagnetic coupling between an antenna housed in the contactless card and a second antenna located in the reader. For developing, storing and processing the information, the card is equipped with a chip acting as a memory zone and a microprocessor, which is connected to the antenna.
Another application of contactless smart cards, which is becoming increasingly important, is their use for the identification of objects designed for sale or rental such as books, disks (CD ROM or DVD). In this application, the chip of the card placed on each object contains in memory the identification data of the object, which thus allows the object to be indexed and identified when it is made available to a buyer (in the case of a sale) or a subscriber (in the case of a rental).
Systems for reading labels placed on the cover page of books placed on shelves of a library are available on the market. In this system, the portable reader includes a reading antenna placed on a flat support.
During reading, the flat support is held parallel to the label to be read so that the electromagnetic field provided by the antenna of the reader can close perpendicular to the plane of the label. It is therefore the field lines at the edge of the antenna that are mainly used and this requires the antenna edge to be kept very close to the binding of books, that is at a distance of about 1 cm. Insofar as the bindings are not necessarily aligned, certain books that are shifted to the rear will thus be too far away and will not be detected when the reader passes in front of the books. The antenna must therefore be plated against the bindings of books to be identified whatever be the position of this binding on the shelf, which restricts the effectiveness of the reader as well as the speed of execution.